Edition-based redefinition (EBR)

Edition-Based Redefinition (EBR)

Edition-based redefinition (EBR) enables online application upgrade with uninterrupted availability of the application. When the installation of an upgrade is complete, the pre-upgrade application and the post-upgrade application can be used at the same time. Therefore, an existing session can continue to use the pre-upgrade application until its user decides to end it; and all new sessions can use the post-upgrade application. When there are no longer any sessions using the pre-upgrade application, it can be retired. In this way, EBR allows hot rollover from from the pre-upgrade version to the post-upgrade version, with zero downtime.

EBR enables online application upgrades in the following manner:

Code changes are installed in the privacy of a new edition.

Data changes are made safely by writing only to new columns or new tables not seen by the old edition. An editioning view exposes a different projection of a table into each edition to allow each to see just its own columns.

Crossedition triggers propagate data changes made by the old edition into the new edition’s columns, or (in hot-rollover) vice-versa.

EBR is available for use in all editions of Oracle Database without the need to license it.